Quote:
Originally Posted by Dr Sardonicus
I would say 2 (a = b = 1).

I should have said I was interested in odd primes only (and the number 1 is not prime).
Therefore a and b cannot both be odd. And as said by science_man_88 above, additionally a and b must be coprime.
These comments imply that a and b are distinct. Without loss of generality, a > b > 0.
/JeppeSN